let obj = {
    a: 'hello',
    b: 666,
    c: undefined,
    d: null,
    e: NaN,
    f: Infinity,
    g: new Date(),
    h: {
        x: 1,
        y: 2,
        toJSON: function () {
            return this.x + this.y;
        }
    }
};
console.log(typeof obj);
let json = JSON.stringify(obj, null, 4);
console.log(json);
console.log(typeof json);
let info = JSON.parse(json);
console.log(info);
console.log(typeof info);
